Manchester bombing attack on the innocent MUST be the final straw in battle against terror

London Mayor Sadiq Kahn says terrorist attacks are “part and parcel of living in a big city”. He is wrong.

While the stoical citizens of Manchester are returning to business as usual, the Government must not.

The horrific slaughter of our children enjoying a night out in a British city must be the last straw. The gloves must now come off.

Our police and security services do an outstanding job. They have successfully stopped hundreds of lethal Islamic terrorist attacks in this country since 9/11 and because of their painstaking work thousands of terrorists are behind bars.

But despite the skill and dedication of the officers of MI5, intelligence is not an exact science and never will be.

The killing of Drummer Lee Rigby four years to the day before Manchester and the ramming and knife attack in Westminster exactly two months before show that some attacks will get through.

Monday’s Manchester bombing was in a different league. It was the first serious explosive attack in Britain since July 2005, when I was a member of Cobra, the crisis committee chaired by the Prime Minister at the time.

Tony Blair wanted to take the gloves off then, but his advisers urged caution so they stayed on.

As with those attacks, I would be surprised if the Manchester bomber, and the terrorist network that almost certainly supported him, are unknown to MI5.

So how did he get through? Because MI5 are inundated with targets.

The Director General estimated that at least 3,000 people in this country are suspected of involvement in extremist activity.

That is far too many to monitor, so some, like the Manchester bomber, go unwatched.

The government must make MI5’s job easier, by reducing the number of terrorist suspects in this country.

All non-British citizens involved in extremism must be deported – that includes those preaching, financing, supporting or preparing for terrorism. Dual citizens must be stripped of British citizenship and deported.

Those who leave the UK to murder, rape and torture with the Islamic State or other jihadist groups must not be allowed to return. They are the most dangerous – blooded in battle and trained in sophisticated acts of mass violence.

Internment must be seriously considered for British citizens who cannot be deported or prosecuted yet intelligence shows are involved in terrorism.

These are draconian measures and they may well infringe the human rights of terrorists. But better that than to leave them free to violently deprive innocent British men, women and children of their lives.

How many more scenes of carnage on our streets must we endure, with teenage boys and girls ripped apart by explosives and shrapnel designed to cause maximum death, wounding and disfigurement, before we take serious action?

• Colonel Richard Kemp is former Chairman of the Cobra Intelligence Group and former Head of Cabinet Office International Terrorism Team